Early in the game if I removed a party member they would be right where I left them when I came back. Now when I change party members the old one's walk off and call me names???

Is your party member Branwin? I faced the same problem when I removed her from my party roster. I suspect she was probably dissatisfied with my party reputation (around 20) since she's Neutral in alignment.

My rep is 18 (thanks to actually playing my LG alignment) - will she leave us if we get too goody-goody? Is it wise then to swap her for Ajantis?

Silke

Neutral characters will get pissed at too high or too low reputation, but they never get angry enough to leave. If your rep is above 18, evil chars will attack you, if you drop below 3, your good chars will leave. Otherwise there should be no problems.